1. Field of the Invention
The invention relates to improvements in ovens with catalytic converters.
2. Description of the Prior Art
It is known to use catalytic converters in ovens in order to reduce the smoke output of ovens, particularly when the ovens are used to cook foods containing fat or grease which is likely to evaporate during the cooking process and cause smoke problems. For example, the present applicant's earlier International Patent Application No. PCT/GB00/04156 (WO 01/38798) describes an oven (2) having catalytic converters (38, 40) positioned outside of a cooking chamber (4). The catalytic converters (38, 40) are positioned downstream of grease filters (34, 36) and upstream of fans (26, 28) which are used to drive air out of the cooking chamber (4), along ducting (19), passed a heating element (20), and back into the cooking chamber (4) through perforations formed in the rear wall (10) of the cooking chamber (4). The grease filters (34, 36), catalytic converters (38, 40) and fans (26, 28) are all located outside of the walls of the cooking chamber (4).
German patent DE 3,636,622 describes an oven in which air is drawn through the centre of a baffle plate (3) by a fan (7), and forced outwardly through a concentric heating element (8) which is provided with strips (9) which are provided with a catalytic coating in order to reduce the smoke and odour content of the air. The strips (9) are connected to the heating element 8 so that they reach the temperature required to achieve the catalytic effect. The air then passes around the edges of the baffle plate (3) and back into the cooking chamber. It will be noted that the catalytic converter strips (9) are therefore located downstream of both the fan (7) and the heating element (8).
German patent DE 4,139,904 shows an oven having a similar arrangement. A fan (6) is used to draw air from a cooking chamber through the centre of a baffle plate (4), and to force the air outwardly through a concentric heating element (7) and then through a concentric catalytic converter (8). The catalytic converter (8) is formed from a porous sponge-like wire mesh on which a catalyst is deposited as a coating. The air then passes back around the edges of the baffle plate (4) into the cooking chamber. It will again therefore be noted that the catalytic converter (8) is located downstream of the fan (6) and heating element (7).
The invention seeks to provide an improved oven having a catalytic converter, which overcomes at least some of the disadvantages of the prior art.